Arrangement for detachably securing a grinding wheel or a group of grinding wheels on a wheel spindle

ABSTRACT

Arrangement for releasably fastening a grinding wheel or a group of grinding wheels ( 1, 3, 5 ) on a wheel spindle ( 9 ), in particular for a spectacle-lens-edging machine, having a grinding-wheel-retaining shaft ( 13 ) which is arranged, in an axially displaceable manner, in a coaxial bore ( 11 ) of the wheel spindle, a retaining disk ( 20 ) which can be fastened in a releasable manner at the free end of the grinding-wheel-retaining shaft, and clamping elements ( 17, 18, 19 ) between the wheel spindle and the grinding-wheel-retaining shaft for axially bracing and releasing the grinding wheel or the group of grinding wheels between the wheel spindle and the retaining disk.

[0001] The invention relates to an arrangement for releasably securing a grinding wheel or a group of grinding wheels on a wheel spindle, in particular for a spectacle-lens-edging machine, as has been described, for example, in DE 195 27 222 C2 from the same applicant.

[0002] Grinding wheels or groups of grinding wheels are secured in a releasable manner predominantly on a wheel spindle, in order for it to be possible for them to be exchanged if, for example, they have become worn or if, in respect of different machining operations, they are to be exchanged.

[0003] Grinding wheels for spectacle-lens-edging machines are usually provided with a cylindrical region and a grooved region, in order, in the first instance, to use the cylindrical region to premachine a spectacle lens which is to be ground to shape and, thereafter, to use the grooved region to form a bevel on the circumference of the shaped spectacle lens. Use is often made of groups of, for example, three grinding wheels, of which one grinding wheel is provided for machining plastic lenses, a cylindrical grinding wheel is provided for the rough grinding of spectacle lenses made of silicate glass and a grinding wheel with a bevel groove is provided for precision or fine machining and beveling.

[0004] The wheel spindle and the grinding wheels are arranged on the spectacle-lens-edging machine in a grinding chamber which can be closed on all sides, since the abraded material which is produced during grinding should not pass to the outside and a cooling lubricant, which should not pass to the outside either, is usually sprayed into the grinding region between the grinding wheel and the spectacle lens. This grinding chamber is kept as small as possible, but a spray guard is usually also arranged tightly around the grinding wheels, said spray guard only leaving the grinding region exposed and having regions which are designed as contact shoes and on which the unmachined lens and/or the ground-to-shape spectacle lens is positioned in order to be measured.

[0005] It can be gathered, from this construction of a conventional spectacle-lens-edging machine, that confined space conditions prevail in the grinding chamber, and these make it very difficult to exchange grinding wheels or groups of grinding wheels since, in the case of the known spectacle-lens-edging machines, the grinding wheels are connected to the wheel spindle such that a grinding-wheel-retaining shaft, which is connected integrally to the wheel spindle and has a smaller diameter than the wheel spindle, has a sleeve positioned on it, the length of the latter being somewhat smaller than the width of the grinding wheel or of the group of grinding wheels. This sleeve bears the grinding wheels and centers them, while bracing with the wheel spindle takes place by means of a retaining disk, of which the diameter is greater than the diameter of the sleeve and which can be screwed to the grinding-wheel-retaining shaft and thus braces the grinding wheel with the wheel spindle.

[0006] It can be gathered from this that, for the purpose of removing the grinding wheels, there has to be sufficient space in the grinding chamber in order for it to be possible for the grinding wheels to be withdrawn from the grinding-wheel-retaining shaft, and removed from the grinding chamber, individually or together.

[0007] Furthermore, there also has to be sufficient space in the grinding chamber in order for it to be possible to attach to the screw connection for the retaining disk a suitable wrench, for the purpose of clamping and releasing the connection. Finally, there is also a double tolerance between the grinding-wheel-retaining shaft and the sleeve and the sleeve and the grinding wheel or the group of grinding wheels, said double tolerance adversely affecting the concentric-running properties.

[0008] If the initially mentioned spray guard with the contact shoes is present, it likewise has to be removed before the grinding wheel or the group of grinding wheels is removed.

[0009] In the case of the known spectacle-lens-edging machines, the task of exchanging a grinding wheel or a group of grinding wheels is thus time-intensive and requires a certain amount of skill.

[0010] The invention is based on the problem of facilitating the installation and the removal of grinding wheels or groups of grinding wheels on wheel spindles with confined space conditions in the axial direction and of ensuring improved concentric-running properties.

[0011] Taking this as the departure point, the invention proposes an arrangement which is intended for releasably securing a grinding wheel or a group of grinding wheels on a wheel spindle, in particular for a spectacle-lens-edging machine, and in the case of which the invention provides a grinding-wheel-retaining shaft which is arranged with a close fit, in an axially displaceable manner, in a coaxial bore of the wheel spindle, which can be retracted into the wheel spindle by at least the width of a grinding wheel, on which a grinding wheel or a group of grinding wheels is seated directly and without play, and at the free end of which a retaining disk can be secured in a releasable manner, clamping elements between the wheel spindle and the grinding-wheel-retaining shaft ensuring the axial bracing and release of the grinding wheel or of the group of grinding wheels between the wheel spindle and the retaining disk and also the retraction of the grinding-wheel-retaining shaft into the wheel spindle by at least the width of a grinding wheel.

[0012] In the case of the arrangement according to the invention, the grinding wheel or the group of grinding wheels is seated directly and without play on the grinding-wheel-retaining shaft, this doing away with the prior-art double tolerance between the grinding-wheel-retaining shaft and the sleeve.

[0013] In order to exchange a grinding wheel or a group of grinding wheels, the bracing of the grinding wheel or of the group of grinding wheels between the wheel spindle and the retaining disk is released by displacement of the grinding-wheel-retaining shaft within the wheel spindle in the direction of the grinding wheel or of the group of grinding wheels, whereupon the retaining disk can be removed from the grinding-wheel-retaining shaft without the aid of a tool. Thereafter, the grinding-wheel-retaining shaft is displaced in the opposite direction within the wheel spindle to the extent where its free end completely frees the grinding wheel, or at least one grinding wheel of a group of grinding wheels, and this can be removed from the grinding chamber without axial displacement from the region of the wheel spindle. Analogously, the procedure takes place in reverse for the purpose of inserting a grinding wheel or a group of grinding wheels. To this end, the new grinding wheel or the group of grinding wheels is positioned in the region of the wheel spindle in the grinding chamber when the grinding-wheel-retaining shaft has been retracted, the grinding-wheel-retaining shaft is extended out of the wheel spindle, and guided through the accommodating bore in the grinding wheel or in the group of grinding wheels, the retaining disk is secured at the free end of the grinding-wheel-retaining shaft, and the grinding-wheel-retaining shaft is moved in the opposite direction for the purpose of bracing the grinding wheel or the group of grinding wheels between the wheel spindle and the retaining disk.

[0014] The retaining disk can be screwed to the free end of the grinding-wheel-retaining shaft, for example by means of a through-bolt or of a threaded pin connected to the retaining disk, without a special tool being necessary in order to release this screw connection, since the bracing of the grinding wheel or of the group of grinding wheels between the wheel spindle and the retaining disk takes place by axial displacement of the grinding-wheel-retaining shaft and the screw connection of the retaining disk can be rotated freely once the bracing has been eliminated.

[0015] It is also possible, according to another embodiment, for the retaining disk to be connected to the free end of the grinding-wheel-retaining shaft in the manner of a bayonet connection. In this case too, the retaining disk can be released from the grinding-wheel-retaining shaft without the aid of a tool, while release is not possible in the braced state.

[0016] The clamping elements between the wheel spindle and the grinding-wheel-retaining shaft may comprise a threaded connection between the grinding-wheel-retaining shaft and the wheel spindle. For this purpose, it is possible either for the externally threaded grinding-wheel-retaining shaft to be screwed directly into a threaded bore in the wheel spindle or for the grinding-wheel-retaining shaft to have a threaded bore for a headed bolt, which is supported on the wheel spindle via a flanged bushing.

[0017] The grinding-wheel-retaining shaft screwed into the wheel spindle can be manually rotated in the bore of the wheel spindle using a suitable handle, a tool then possibly being necessary for tightening purposes. In the case of a headed bolt being used for displacing and bracing the grinding-wheel-retaining shaft, it is possible to utilize, for example, a hexagon-socket wrench.

[0018] In order to speed up the operations of screwing in and unscrewing the grinding-wheel-retaining shaft in the bore of the wheel spindle or the headed bolt, and to be able to dispense with clamping tools, it is possible for a, for example, electric rotary drive to be arranged between the wheel spindle and the grinding-wheel-retaining shaft or the headed bolt.

[0019] It is likewise possible to provide, as clamping elements, a hydraulic or pneumatic piston/cylinder unit between the grinding-wheel-retaining shaft and the wheel spindle, said unit providing both for the quick axial displacement of the grinding-wheel-retaining shaft in the bore of the wheel spindle and for the bracing. This arrangement provides the quickest possible actuation.

[0020] The invention is explained in more detail hereinbelow with reference to an exemplary embodiment illustrated in the drawing.

[0021] The drawing shows part of a spectacle-lens-edging machine in cross section, with a group of grinding wheels on a wheel spindle.

[0022] Of the spectacle-lens-edging machine, only a housing neck 8, in which a wheel spindle 9 is mounted by means of a pair of rolling-contact bearings 10, is illustrated.

[0023] A group of grinding wheels, comprising a grinding wheel 1 for plastic, with a metal ring 2 in which diamond abrasive materials have been metalically bound, a rough-grinding wheel for silicate glass, with a likewise metal ring 4 in which diamond abrasive materials have been metalically bound, and a precision-grinding wheel 5, with a ring 6 which is of the same design and has a bevel groove 7 for forming a ridge bevel on the circumference of a ground-to-shape spectacle lens, is seated on a grinding-wheel-retaining shaft 13, which has been introduced with a close fit into a bore 11 of the wheel spindle 9. The grinding-wheel-retaining shaft 13 has a threaded bore 14 and a cylindrical bore 15, which is coaxial with the threaded bore and has a somewhat larger diameter. Starting from the free end, diametrically opposite, angled slots 16 for a bayonet securing means, which will be described at a later stage in the text, are made in the grinding-wheel-retaining shaft 13.

[0024] A headed bolt 17 with a hexagon-socket head 18 is screwed into the threaded bore 14. The head 18 is supported, via a flanged bushing 19, on the wheel spindle 9, into which the flanged bushing 19 is adhesively bonded.

[0025] For the purpose of bracing the group of grinding wheels 1, 3, 5 with the wheel spindle 9, a retaining disk 20 is inserted into the bore 15 by way of its cylindrical extension 21, on which radial studs 22 are located, such that the radial studs 22 and the cylindrical extension 21 pass into the angled slots 16 and, by virtue of rotation, form the above-mentioned bayonet connection. A compression spring 23 is supported between the cylindrical extension 21 and a shoulder at the end of the bore 15 in the grinding-wheel-retaining shaft 13. If the headed bolt 17 is then rotated such that the grinding-wheel-retaining shaft 13 is retracted into the bore 11 of the wheel spindle 9, the retaining disk 20 comes into abutment against the group of grinding wheels 1, 3, 5 and braces the latter, via a supporting disk 12, with the wheel spindle 9.

[0026] For release purposes, the headed bolt 17 is rotated in the opposite direction until it reaches the position illustrated. The retaining disk 20 can then be easily removed. If, by virtue of the headed bolt 17 being rotated again in the direction which also serves for clamping purposes, the grinding-wheel-retaining shaft 13 is then retracted into the wheel spindle 9 to the extent where the end of the grinding-wheel-retaining shaft 13 is guided out of the accommodating bore of the grinding wheel 5, the latter can be removed radially from the region of the grinding-wheel-retaining shaft 13.

[0027] The grinding-wheel-retaining shaft 13 can also be retracted into the wheel spindle 9 to the extent where the entire group of grinding wheels 1, 3, 5 can be removed in the radial direction.

[0028] The procedure takes place in reverse for the purpose of inserting a group of grinding wheels 1, 3, 5.

[0029] Instead of moving the grinding-wheel-retaining shaft 13 by means of a headed bolt 17 in the bore 11 of the wheel spindle 9, it is also possible for the grinding-wheel-retaining shaft 13 to be screwed directly into a corresponding threaded bore of the wheel spindle 9. In this case, the grinding-wheel-retaining shaft 13 is preferably guided out of the wheel spindle 9 into the region of the flanged bushing 19, which is illustrated for the embodiment with headed bolt 17, and it can be provided here with a handwheel, which can be used for rotating the grinding-wheel-retaining shaft 13 in the wheel spindle 9.

[0030] In order to speed up an operation for exchanging a group of grinding wheels 1, 3, 5 or a single grinding wheel, the headed bolt 17 may be designed as a threaded spindle which can be rotated by means of an electromotive drive. A similar drive may also be provided in the embodiment in which the grinding-wheel-retaining shaft 13 is screwed directly into the wheel spindle 9.

[0031] Furthermore, it is also possible to arrange a hydraulic or pneumatic piston/cylinder unit between the wheel spindle 9 and the grinding-wheel-retaining shaft 13, said unit providing both for the quick displacement of the grinding-wheel-retaining shaft 13 in relation to the wheel spindle 9 and for the bracing of the grinding wheels 1, 3, 5. 

1. An arrangement for releasably securing a grinding wheel or a group of grinding wheels (1, 3, 5) on a wheel spindle (9), in particular for a spectacle-lens-edging machine, having a grinding-wheel-retaining shaft (13) which is arranged with a close fit, in an axially displaceable manner, in a coaxial bore (11) of the wheel spindle (9), can be retracted into the wheel spindle (9) by at least the width of a grinding wheel (1, 3, 5) and on which a grinding wheel or a group of grinding wheels (1, 3, 5) is seated directly and without play, a retaining disk (20) which can be secured in a releasable manner at the free end of the grinding-wheel-retaining shaft (13), and clamping elements (17, 18, 19) between the wheel spindle (9) and the grinding-wheel-retaining shaft (13) for axially bracing and releasing the grinding wheel or the group of grinding wheels (1, 3, 5) between the wheel spindle (9) and the retaining disk (20) and for retracting the grinding-wheel-retaining shaft (13) into the wheel spindle (9) by at least the width of a grinding disk (1, 3, 5).
 2. The arrangement as claimed in claim 1, in the case of which the retaining disk (20) can be screwed to the free end of the grinding-wheel-retaining shaft (13).
 3. The arrangement as claimed in claim 1, in the case of which the retaining disk (20) has an extension (21) which interacts with the free end of the grinding-wheel-retaining shaft (13) in the manner of a bayonet connection (16, 22).
 4. The arrangement as claimed in one of claims 1 to 3, having a screw connection (14, 17, 18, 19) between the grinding-wheel-retaining shaft (13) and the wheel spindle (9).
 5. The arrangement as claimed in claim 4, in the case of which the grinding-wheel-retaining shaft (13) has a threaded bore (14) for a headed bolt (17), which is supported on the wheel spindle (9) via a flanged bushing (19).
 6. The arrangement as claimed in claim 4 or 5, having a rotary drive between the grinding-wheel-retaining shaft (13) and the wheel spindle (9).
 7. The arrangement as claimed in one of claims 1 to 3, in the case of which the clamping elements comprise a hydraulic or pneumatic piston/cylinder unit between the grinding-wheel-retaining shaft (13) and the wheel spindle (9). 